Virtually anyone on SDN who takes an MCAT prep course takes Kaplan, The Princeton Review (TPR) or Exam Krackers (EK). Kaplan is suited to you if you want someone giving reviews/lectures on all the subject material, and EK is more suited to you if you study best by yourself. I took Kaplan because I needed a steady influx of study material (I would've procrastinated otherwise). I don't know much about TPR, but the MCAT forum explains many of these things.
Like Yzia said, just because the average acceptance numbers are lower doesn't mean that you aren't competing with a lot of other people. Not sure why MCW was mentioned - the average MCAT there is a 30, which is the average matriculant's score overall, but if you are in-state at Wisconsin, you've got a good chance in getting in there. It does have a large incoming class though, which helps your chances.